What version of the libc package does ANPM show as installed?
What was the last thing you successfully updated with ANPM?
>how is that possible since i've libc066.dll under \usr\lib
>which is in libpath?
You should not even be asking this question. You should already know that
yum tracks what is installed on your system with the yum/rpm database. If
yum thinks that libc066.dll is not installed, it is because the database
indicates this.
There are any number of reasons why yum might be doing this. It is
probably time to make use of the ANPM troubleshooting wiki.